EP0291169A1 - Disposition de protection pour un circuit d'interface de ligne téléphonique d'abonné - Google Patents

Disposition de protection pour un circuit d'interface de ligne téléphonique d'abonné Download PDF

Info

Publication number
EP0291169A1
EP0291169A1 EP88303286A EP88303286A EP0291169A1 EP 0291169 A1 EP0291169 A1 EP 0291169A1 EP 88303286 A EP88303286 A EP 88303286A EP 88303286 A EP88303286 A EP 88303286A EP 0291169 A1 EP0291169 A1 EP 0291169A1
Authority
EP
European Patent Office
Prior art keywords
line
voltage
current
switching means
responsive
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP88303286A
Other languages
German (de)
English (en)
Other versions
EP0291169B1 (fr
Inventor
Reinhard Werner Rosch
Stanley Daniel Rosenbaum
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nortel Networks Ltd
Original Assignee
Northern Telecom Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Northern Telecom Ltd filed Critical Northern Telecom Ltd
Priority to AT88303286T priority Critical patent/ATE83882T1/de
Publication of EP0291169A1 publication Critical patent/EP0291169A1/fr
Application granted granted Critical
Publication of EP0291169B1 publication Critical patent/EP0291169B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M1/00—Substation equipment, e.g. for use by subscribers
    • H04M1/738—Interface circuits for coupling substations to external telephone lines
    • H04M1/74—Interface circuits for coupling substations to external telephone lines with means for reducing interference; with means for reducing effects due to line faults
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/02—Details
    • H02H3/06—Details with automatic reconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
    • H02H3/087—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current for dc applications
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M3/00—Automatic or semi-automatic exchanges
    • H04M3/18—Automatic or semi-automatic exchanges with means for reducing interference or noise; with means for reducing effects due to line faults with means for protecting lines

Definitions

  • This invention relates to a protection arrangement for a telephone subscriber line interface circuit, referred to below as a SLIC.
  • Jakab U.S. Patent No. 4,467,310 issued August 21, 1984 and entitled “Telephone Subscriber Line Battery Feed Resistor Arrangements” describes an arrangement in which a switching type PTC thermistor is connected in series with and forms part of a battery feed resistor with which it is in close thermal contact. Whilst such an arrangement is effective, it has a relatively high cost because it requires the use of closely matched thermistors in order to provide the necessary very close matching of resistances in the subscriber line wires.
  • Such an arrangement has certain disadvantages in that the thresholds for protection from excessive currents and excessive voltages are not sufficiently independent of one another or of the nature of the fault (e.g. whether a fault condition applies to both wires or only one wire of the subscriber line), there is a risk of chattering of the isolation relay under some fault conditions, and there is a risk of a latched condition arising following operation of the isolation relay for conventional purposes.
  • an object of this invention is to provide an improved protection arrangement for a SLIC.
  • a protection arrangement for a telephone subscriber line interface circuit connected to a telephone subscriber line comprising: switching means; voltage sensing means: current sensing means; means for coupling the voltage sensing means to the line and for coupling the current sensing means to the line via the switching means, whereby the voltage sensing means is responsive to voltage on the line and the current sensing means is responsive, when the switching means is closed, to current on the line; and control means for closing the switching means in normal operation and for opening the switching means in response to an excessive voltage on the line determined by the voltage sensing means and/or an excessive current on the line determined by the current sensing means.
  • the invention is based on the recognition that either an excessive voltage or an excessive current, or both, may occur on the line and present a need for protection.
  • This protection is provided by the opening of the switching means, but this interrupts the current.
  • a relatively high impedance is presented to the SLIC end of the line so that voltage on the line due to a fault may rise sufficiently that it becomes an excessive voltage even if it was not excessive before the current interruption. Sensing of the voltage on the line continues after opening of the switching means, the excessive voltage then maintaining an open state of the switching means so that chattering is avoided.
  • the voltage and current sensing means comprise means for producing a voltage dependent upon the voltage and current, respectively, on the line
  • the control means comprises integrating means responsive to the voltages and comparison means responsive to an output of the integrating means exceeding a predetermined threshold for opening the switching means.
  • the integrating means comprises a capacitor and the comparison means comprises a trigger circuit responsive to a voltage to which the capacitor is charged, and the control means comprises means for charging the capacitor when the voltage produced by the current sensing means exceeds a reference voltage.
  • the switching means comprises contacts of an isolation relay which is typically already provided for the telephone subscriber line, and the control means is responsive to an isolation control signal for opening the switching means and discharging the capacitor.
  • the discharging of the capacitor avoids a locked-up state occurring when the isolation control signal is removed, in the event that excessive voltages are present on the line while it is not properly terminated due to the open relay contacts.
  • Such excessive voltages may be acceptable if, for example, they are due to induction from a power line and result in only a small, not excessive, line current when the relay contacts are closed and the line is properly terminated.
  • control means is preferably responsive to a ringing control signal for discharging the capacitor, to prevent high ringing voltages on the line from causing the switching means to be opened.
  • the voltage sensing means is responsive to only one polarity of voltage on the line and the current sensing means is responsive, when the switching means is closed, to only one polarity of current on the line, said one polarity of current corresponding to a voltage on the line of polarity opposite to said one polarity of voltage.
  • the invention also extends to a method of protecting a telephone subscriber line interface circuit (SLIC) from excessive voltage and/or current on a telephone subscriber line to which the SLIC is connected, comprising the steps of: providing switching means between the SLIC and the line, the switching means being closed in normal operation to connect the SLIC to the line; sensing current on the line on the SLIC side of the switching means; sensing voltage on the line on the line side of the switching means; and opening the switching means in response to an excessive sensed current and/or voltage.
  • SLIC telephone subscriber line interface circuit
  • a SLIC and protection arrangement is illustrated coupled to a 2-wire telephone subscriber line 10 comprising tip and ring wires T and R respectively.
  • a current sensing circuit 12 is coupled to two closely matched battery feed resistors of the SLIC, which are coupled in series with the tip and ring wires via the contacts of an isolation relay 14.
  • the isolation relay is conventionally provided for cut-over purposes, and to isolate the SLIC from the line 10 for example for testing purposes, in each case being controlled by software of a telephone switch to which the line 10 is connected via the SLIC.
  • the relay 14 is also controlled by a control circuit 16 in dependence upon line currents, sensed by the current sensing circuit 12, on the SLIC side of the relay contacts, and in dependence upon line voltages, sensed by a voltage sensing circuit 18, on the line side of the relay contacts.
  • a control circuit 16 in dependence upon line currents, sensed by the current sensing circuit 12, on the SLIC side of the relay contacts, and in dependence upon line voltages, sensed by a voltage sensing circuit 18, on the line side of the relay contacts.
  • the current sensing circuit 12 in Fig. 2 comprises cross-connected potential dividers formed by resistors 24 coupled to the closely matched feed resistors 22, and a current summing d.c. amplifier, comprising an operational amplifier 26, input resistors 28, and feedback resistors 29, having an output line 30 on which there is produced a voltage representative of current through the feed resistors 22.
  • the arrangement of the resistors 24 is known for example from Rosenbaum et al. United States Patent No. 4,514,595 issued April 30, 1985 and entitled "Active Impedance Line Feed Circuit".
  • the feed resistors 22 are coupled to the tip and ring wires T and R of the line 10 via the contacts 32 of the isolation relay 14, which also comprises a relay coil 34.
  • the voltage sensing circuit 18 comprises two diodes 36, each connected between a respective one of the tip and ring wires T and R and a junction point 38 and poled to be normally reverse biassed by the d.c. which is conventionally applied to the telephone subscriber line 10, a potential divider comprising resistors 40 and 42 connected between the junction point 38 and ground, and an optional resistor 44 and a diode 46 connected in series between the tapping point of the potential divider and an output line 48 of the voltage sensing circuit.
  • the control circuit 16 comprises a capacitor 50, a voltage comparator 52, a controlled current source 54, a current sink 56, a Schmitt trigger circuit 58, an NPN buffer transistor 60, and NPN transistors 62, 64, 66, 68, and 70 each including a current-limiting resistor (not referenced for the sake of clarity) in series with its base.
  • the control circuit 16 includes input terminals 72 and 74 for control signals CI and RI respectively which are discussed further below. Components to the right of a broken line A-B shown in Fig. 2 may be conveniently provided with other parts of the SLIC, not shown in Fig. 2, in one or more integrated circuit devices.
  • the capacitor 50 is connected between the line 48 and ground, whereby it can be charged via the optional resistor 44 (which provides an increased charging time constant if desired) and the diode 46 from the potential divider of the voltage sensing circuit 18 during a positive half-cycle of an a.c. potential (or in the presence of a positive d.c. potential) on either or both wires of the subscriber line 10.
  • the comparator 52 has an inverting input connected to the output line 30 of the current sensing circuit 12, a non-inverting input connected to a reference voltage VREF, and an output which controls the current source 54.
  • the current sink 56 is connected between the line 48 and ground and passes a constant current ID to provide a slow discharge path for the capacitor 50.
  • the line 48 is also connected to the input of the Schmitt trigger circuit 58, which is triggered in the event that the capacitor 50 is charged to a predetermined trigger voltage, thereby energizing the isolation relay coil 34, to open the contacts 32, via the buffer transistor 60 and the transistor 62 which acts as an isolation relay driver.
  • the isolation relay coil 34 is de-energized and the contacts 32 are closed.
  • the control signal CI can be applied to the terminal 72, rendering the transistors 64 and 66 coupled to this terminal conductive.
  • the transistor 66 turns on the isolation relay driver transistor 62 to energize the isolation relay coil 34 as described above, and the transistor 64 discharges the capacitor 50.
  • the discharging of the capacitor 50 inhibits operation of the protection arrangement while the control signal CI is present, and hence in the presence of high induced voltages which may occur on the line 10 in the absence of a proper line termination via the SLIC. This inhibition avoids a latched condition, in which the relay coil 34 would remain energized, when the control signal CI is terminated.
  • the transistor 68 is turned on, to discharge the capacitor 50, by the control signal RI, which is applied to the terminal 74 to energize a ringing relay driver (not shown) to apply ringing voltages to the line 10.
  • the ringing voltages could otherwise themselves cause the capacitor 50 to be charged sufficiently to trigger the Schmitt trigger circuit 58.
  • the transistor 70 is turned on to clamp the terminal 74 to ground, so that the ringing relay can not be energized in the presence of, and hence ringing equipment can not be damaged by, excessive voltages on the line 10.
  • an excessive voltage and/or current on the line 10 results in charging of the capacitor 50, triggering of the circuit 58, and consequent opening of the contacts 32 thereby to protect the SLIC from the excessive voltage or current.
  • the current source 54 is turned on, the capacitor 50 is charged, and the circuit 58 triggered to open the contacts 32 thereby interrupting the current.
  • the opening of the contacts 32 removes the relatively low impedance termination of the line by the SLIC (the voltage sensing circuit potential divider has a high impedance), so that the line voltage rises and the charged state of the capacitor 50 is maintained during positive half cycles via the voltage sensing circuit.
  • the threshold levels provided by the reference voltage VREF and the Schmitt trigger circuit 58, the division ratio of the potential divider in the voltage sensing circuit, and the rates of charging and discharging the capacitor 50 via the components 46, 54, and 56 can all be independently determined to provide for desired operating characteristics.
  • the capacitor 50 may be conveniently charged with a time constant of about 3ms and discharged with a time constant of about 200ms to avoid chattering of the isolation relay at the frequency of the excessive current or voltage.
  • the capacitor 50 In the presence of an excessive alternating voltage, without an excessive current, on the line 10 the capacitor 50 is charged via the diode 46 during positive half cycles, whereby the isolation relay contacts 32 are opened as described above. In the event of a major fault condition, simultaneously causing both excessive alternating voltage and current on the line 10, the capacitor 50 will be charged, and the contacts 32 opened, via the diode 46 or the current source 54 within one half cycle, whereby rapid protection is achieved.

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Interface Circuits In Exchanges (AREA)
  • Exchange Systems With Centralized Control (AREA)
  • Protection Of Static Devices (AREA)
  • Emergency Protection Circuit Devices (AREA)
  • Devices For Supply Of Signal Current (AREA)
EP88303286A 1987-05-15 1988-04-13 Disposition de protection pour un circuit d'interface de ligne téléphonique d'abonné Expired - Lifetime EP0291169B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT88303286T ATE83882T1 (de) 1987-05-15 1988-04-13 Schutzanordnung fuer eine fernsprechteilnehmerschnittstellen-schaltung.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CA537286 1987-05-15
CA000537286A CA1260171A (fr) 1987-05-15 1987-05-15 Dispositif de protection pour circuit d'interface de ligne d'abonne du telephone

Publications (2)

Publication Number Publication Date
EP0291169A1 true EP0291169A1 (fr) 1988-11-17
EP0291169B1 EP0291169B1 (fr) 1992-12-23

Family

ID=4135677

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88303286A Expired - Lifetime EP0291169B1 (fr) 1987-05-15 1988-04-13 Disposition de protection pour un circuit d'interface de ligne téléphonique d'abonné

Country Status (7)

Country Link
EP (1) EP0291169B1 (fr)
JP (1) JPS63304793A (fr)
KR (1) KR960014224B1 (fr)
CN (1) CN1011652B (fr)
AT (1) ATE83882T1 (fr)
CA (1) CA1260171A (fr)
DE (1) DE3876852T2 (fr)

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0388022A2 (fr) * 1989-03-15 1990-09-19 Nortel Networks Corporation Composant semi-conducteur de protection contre les courants de surcharge
WO1990013960A1 (fr) * 1989-04-28 1990-11-15 Northern Telecom Limited Agencement de protection avec remise a l'etat initial automatique pour circuit d'interface de lignes d'abonnes (slic) d'un reseau telephonique
EP0467212A2 (fr) * 1990-07-20 1992-01-22 Siemens Aktiengesellschaft Disposition pour la protection d'un circuit d'alimentation d'un circuit de ligne d'abonné d'un central téléphonique contre des surtensions externes
EP0482466A1 (fr) * 1990-10-24 1992-04-29 STMicroelectronics S.r.l. Dispositif de protection pour circuits téléphoniques électriques et/ou électroniques, conçu pour limiter la puissance interne dissipée
BE1004296A3 (fr) * 1989-07-25 1992-10-27 Korea Inst Sci & Tech Dispositif de protection pour proteger un systeme de commutation, plus particulierement un systeme de commutation automatique de communications.
WO1994001960A1 (fr) * 1992-07-01 1994-01-20 Raychem Limited Interrupteur et circuit de protection actionnes a distance
US5327319A (en) * 1991-08-27 1994-07-05 At&T Bell Laboratories Common mode voltage surge protection circuitry
DE4326596A1 (de) * 1993-08-07 1995-02-09 Alcatel Sel Rft Gmbh Schutzschaltungsanordnung für elektronische Teilnehmerschaltungen
WO1996011543A1 (fr) * 1994-10-06 1996-04-18 Northern Telecom Limited Protection des circuits d'interface actifs des lignes telephoniques
DE19542408C1 (de) * 1995-11-14 1996-11-14 Kurt Hofmann Verfahren und Vorrichtung zur Überwachung von Telefonwählleitungen
US5652575A (en) * 1992-07-01 1997-07-29 Raychem Limited Maintenance termination unit for telephone circuits
WO1997038517A1 (fr) * 1996-04-10 1997-10-16 Advanced Micro Devices, Inc. Detection d'inversion de polarite par courant et tension de boucle
WO2000036809A1 (fr) * 1998-12-17 2000-06-22 Nortel Networks Limited Systeme de protection contre le courant et la tension pour un circuit d'interface de ligne d'abonne telephonique
WO2001019069A1 (fr) * 1999-09-03 2001-03-15 Telefonaktiebolaget Lm Ericsson (Publ) Procede et agencement permettant de raccourcir le temps de recuperation d'une commande de ligne
WO2002027886A2 (fr) * 2000-09-28 2002-04-04 Turnstone Systems, Inc. Systemes et procedes pour proteger un systeme micro-electromecanique (mems) vulnerable et des dispositifs de relais electronique
US6563926B1 (en) 1999-07-27 2003-05-13 Nortel Networks Limited Resetting surge protection in telephone line interface circuits
WO2005074241A1 (fr) * 2004-01-29 2005-08-11 Tyco Electronics Argentina Sa Protection de surtension dans des lignes de telephone/donnees conçue pour des installations a mises a la terre de faible qualite
WO2017106589A1 (fr) 2015-12-17 2017-06-22 Molex, Llc Système de protection contre les surintensités de terre et procédés pour son utilisation
CN109980928A (zh) * 2019-04-24 2019-07-05 北京无线电测量研究所 一种高压输入t/r组件的通道电源故障隔离电路及装置

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5392349A (en) * 1992-05-18 1995-02-21 At&T Corp. Overvoltage protection scheme for subscriber loops and method of performing same
US6782098B1 (en) 2000-04-07 2004-08-24 Uniden Corporation Protection circuit/method for subscriber telephone interface circuit
JP2002237913A (ja) * 2001-02-08 2002-08-23 Nec Eng Ltd Ａｃ混触被害防止装置
TWI641221B (zh) * 2017-05-08 2018-11-11 聯發科技股份有限公司 電子裝置的介面電路
TWI656742B (zh) * 2018-07-31 2019-04-11 慧榮科技股份有限公司 振盪器裝置
CN109963037B (zh) * 2019-03-05 2021-01-08 网经科技（苏州）有限公司 基于虚拟化slic端口的ip pbx用户模块的级联方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4514595A (en) * 1982-06-10 1985-04-30 Northern Telecom Limited Active impedance line feed circuit
WO1986002786A1 (fr) * 1984-10-24 1986-05-09 Om Ahuja Coupe-circuit avec reinitialisation automatique
EP0209973A1 (fr) * 1985-06-18 1987-01-28 Nortel Networks Corporation Dispositif de protection pour une interface jonction d'une ligne d'abonné

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5334305A (en) * 1976-08-12 1978-03-30 Nissan Chemical Ind Ltd Afforestation method of steep slope
JPS593914B2 (ja) * 1978-02-13 1984-01-26 株式会社日立製作所 電話交換機加入者回路の過電流自動遮断方式
JPS5853289A (ja) * 1981-09-24 1983-03-29 Nippon Telegr & Teleph Corp <Ntt> 過電流保護回路
JPS5913489A (ja) * 1982-07-14 1984-01-24 Fujitsu Ltd 過電流保護回路
DE3340927A1 (de) * 1983-11-11 1985-05-23 Siemens AG, 1000 Berlin und 8000 München Schaltungsanordnung zur ableitung von ueberspannungen
JPS6143858A (ja) * 1984-08-07 1986-03-03 Nec Corp 加入者回路の過電流保護回路
JPS6162116A (ja) * 1984-09-03 1986-03-31 Fujitsu Ltd 過電流保護回路
JPS6282859A (ja) * 1985-10-08 1987-04-16 Nec Corp 搬送端局の自動給電方式

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4514595A (en) * 1982-06-10 1985-04-30 Northern Telecom Limited Active impedance line feed circuit
WO1986002786A1 (fr) * 1984-10-24 1986-05-09 Om Ahuja Coupe-circuit avec reinitialisation automatique
EP0209973A1 (fr) * 1985-06-18 1987-01-28 Nortel Networks Corporation Dispositif de protection pour une interface jonction d'une ligne d'abonné

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, vol. 9, no. 234 (E-344)[1957], 20th September 1985; & JP-A-60 086 995 (NIPPON DENKI K.K.) 16-05-1985 *

Cited By (35)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0388022A3 (fr) * 1989-03-15 1991-11-13 Nortel Networks Corporation Composant semi-conducteur de protection contre les courants de surcharge
EP0388022A2 (fr) * 1989-03-15 1990-09-19 Nortel Networks Corporation Composant semi-conducteur de protection contre les courants de surcharge
WO1990013960A1 (fr) * 1989-04-28 1990-11-15 Northern Telecom Limited Agencement de protection avec remise a l'etat initial automatique pour circuit d'interface de lignes d'abonnes (slic) d'un reseau telephonique
US5146384A (en) * 1989-04-28 1992-09-08 Northern Telecom Limited Automatically resetting protection arrangement for a telephone subscriber line interface circuit
BE1004296A3 (fr) * 1989-07-25 1992-10-27 Korea Inst Sci & Tech Dispositif de protection pour proteger un systeme de commutation, plus particulierement un systeme de commutation automatique de communications.
EP0467212A2 (fr) * 1990-07-20 1992-01-22 Siemens Aktiengesellschaft Disposition pour la protection d'un circuit d'alimentation d'un circuit de ligne d'abonné d'un central téléphonique contre des surtensions externes
EP0467212A3 (en) * 1990-07-20 1992-10-14 Siemens Aktiengesellschaft Arrangement for the protection of a feed circuit of a subscriber line circuit of a telephone exchange against external overvoltages
US5519775A (en) * 1990-10-24 1996-05-21 Sgs-Thomson Microelectronics, S.R.L. Device for electrical and/or electronic telephone circuits, designed to limit the power dissipated within them
EP0482466A1 (fr) * 1990-10-24 1992-04-29 STMicroelectronics S.r.l. Dispositif de protection pour circuits téléphoniques électriques et/ou électroniques, conçu pour limiter la puissance interne dissipée
US5327319A (en) * 1991-08-27 1994-07-05 At&T Bell Laboratories Common mode voltage surge protection circuitry
AU681587B2 (en) * 1992-07-01 1997-09-04 Raychem Limited Remotely actuated switch and protection circuit
US5604785A (en) * 1992-07-01 1997-02-18 Raychem Limited Remotely actuated switch and protection circuit
US5652575A (en) * 1992-07-01 1997-07-29 Raychem Limited Maintenance termination unit for telephone circuits
WO1994001960A1 (fr) * 1992-07-01 1994-01-20 Raychem Limited Interrupteur et circuit de protection actionnes a distance
CN1076920C (zh) * 1992-07-01 2001-12-26 雷伊化学有限公司 远距离操纵开关和保护电路
DE4326596A1 (de) * 1993-08-07 1995-02-09 Alcatel Sel Rft Gmbh Schutzschaltungsanordnung für elektronische Teilnehmerschaltungen
EP0913980A3 (fr) * 1994-10-06 2001-04-25 Nortel Networks Limited Protection des circuits d'interface actifs des lignes téléphoniques
WO1996011543A1 (fr) * 1994-10-06 1996-04-18 Northern Telecom Limited Protection des circuits d'interface actifs des lignes telephoniques
EP0913980A2 (fr) * 1994-10-06 1999-05-06 Nortel Networks Corporation Protection des circuits d'interface actifs des lignes téléphoniques
DE19542408C1 (de) * 1995-11-14 1996-11-14 Kurt Hofmann Verfahren und Vorrichtung zur Überwachung von Telefonwählleitungen
WO1997038517A1 (fr) * 1996-04-10 1997-10-16 Advanced Micro Devices, Inc. Detection d'inversion de polarite par courant et tension de boucle
WO2000036809A1 (fr) * 1998-12-17 2000-06-22 Nortel Networks Limited Systeme de protection contre le courant et la tension pour un circuit d'interface de ligne d'abonne telephonique
US6885745B1 (en) 1998-12-17 2005-04-26 Nortel Networks, Ltd. Voltage and protection arrangement for a telephone subscriber line interface circuit
US6563926B1 (en) 1999-07-27 2003-05-13 Nortel Networks Limited Resetting surge protection in telephone line interface circuits
WO2001019069A1 (fr) * 1999-09-03 2001-03-15 Telefonaktiebolaget Lm Ericsson (Publ) Procede et agencement permettant de raccourcir le temps de recuperation d'une commande de ligne
US6507470B1 (en) 1999-09-03 2003-01-14 Telefonaktiebolaget Lm Ericsson Method and arrangement for shortening the recovery time of a line driver
WO2002027886A2 (fr) * 2000-09-28 2002-04-04 Turnstone Systems, Inc. Systemes et procedes pour proteger un systeme micro-electromecanique (mems) vulnerable et des dispositifs de relais electronique
US6671149B1 (en) 2000-09-28 2003-12-30 Turnstone Systems, Inc. Systems and methods for protecting vulnerable micro electro-mechanical system (MEMS) and electronic relay devices
WO2002027886A3 (fr) * 2000-09-28 2003-03-13 Turnstone Systems Inc Systemes et procedes pour proteger un systeme micro-electromecanique (mems) vulnerable et des dispositifs de relais electronique
WO2005074241A1 (fr) * 2004-01-29 2005-08-11 Tyco Electronics Argentina Sa Protection de surtension dans des lignes de telephone/donnees conçue pour des installations a mises a la terre de faible qualite
WO2017106589A1 (fr) 2015-12-17 2017-06-22 Molex, Llc Système de protection contre les surintensités de terre et procédés pour son utilisation
EP3391490A4 (fr) * 2015-12-17 2019-09-04 Molex, LLC Système de protection contre les surintensités de terre et procédés pour son utilisation
US10574049B2 (en) 2015-12-17 2020-02-25 Molex, Llc Ground overcurrent control system and methods of using same
US11114837B2 (en) 2015-12-17 2021-09-07 Molex, Llc Ground overcurrent control system and methods of using same
CN109980928A (zh) * 2019-04-24 2019-07-05 北京无线电测量研究所 一种高压输入t/r组件的通道电源故障隔离电路及装置

Also Published As

Publication number Publication date
KR960014224B1 (ko) 1996-10-14
DE3876852D1 (de) 1993-02-04
JPS63304793A (ja) 1988-12-13
KR880014773A (ko) 1988-12-24
CN1011652B (zh) 1991-02-13
CN1030169A (zh) 1989-01-04
CA1260171A (fr) 1989-09-26
EP0291169B1 (fr) 1992-12-23
DE3876852T2 (de) 1993-04-29
ATE83882T1 (de) 1993-01-15

Similar Documents

Publication Publication Date Title
CA1260171A (fr) Dispositif de protection pour circuit d&#39;interface de ligne d&#39;abonne du telephone
US4709296A (en) Protection arrangement for a telephone subscriber line interface circuit
US4947427A (en) Protection arrangement for a telephone subscriber line interface circuit
EP0470090B1 (fr) Agencement de protection avec remise a l&#39;etat initial automatique pour circuit d&#39;interface de lignes d&#39;abonnes (slic) d&#39;un reseau telephonique
US4060844A (en) Solid state tripping circuit
US4025820A (en) Contactor device including arc supression means
CA2159273C (fr) Protection des circuits d&#39;interface de lignes telephoniques actifs
EP0552273B1 (fr) Agencement de protection de circuit
EP0630533B1 (fr) Dispositif protecteur limitant un courant de court-circuit
EP0571109A2 (fr) Schéma et méthode pour la protection contre les surtensions pour d&#39;une ligne d&#39;abonné
JPS6217454B2 (fr)
CA1319170C (fr) Circuit de protection de circuit a semiconducteur
US6618482B2 (en) System and method for protecting devices connected to a telephone line
JP2589270B2 (ja) 測定機器用結合回路
US4466039A (en) Open circuit current transformer protection circuit
US5721773A (en) Lightning protected maintenance termaination unit
EP0131896A1 (fr) Dispositif de protection contre les surtensions à usage domestique ou industriel
GB2160721A (en) Protection of electrical/electronic equipment
US4106070A (en) Hazardous voltage protector for telephone line
US5940259A (en) Voltage surge protector for electronic circuits with semiconductor components
US5019936A (en) Voltage-to-frequency squared circuit
JP2765943B2 (ja) 電話保護回路
US6850400B2 (en) Circuit for protection against heating of a protection element of equipment
US4325099A (en) Detector circuit for thyristors
SU1097989A1 (ru) Источник питани с защитой

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT DE FR GB NL SE

17P Request for examination filed

Effective date: 19890509

17Q First examination report despatched

Effective date: 19910626

RTI1 Title (correction)
RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: NORTHERN TELECOM LIMITED

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AT DE FR GB NL SE

REF Corresponds to:

Ref document number: 83882

Country of ref document: AT

Date of ref document: 19930115

Kind code of ref document: T

ET Fr: translation filed
REF Corresponds to:

Ref document number: 3876852

Country of ref document: DE

Date of ref document: 19930204

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: AT

Payment date: 19930415

Year of fee payment: 6

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 19930419

Year of fee payment: 6

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: NL

Payment date: 19930430

Year of fee payment: 6

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: AT

Effective date: 19940413

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Effective date: 19940414

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Effective date: 19941101

NLV4 Nl: lapsed or anulled due to non-payment of the annual fee
EUG Se: european patent has lapsed

Ref document number: 88303286.4

Effective date: 19941110

REG Reference to a national code

Ref country code: GB

Ref legal event code: IF02

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20040312

Year of fee payment: 17

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 20040402

Year of fee payment: 17

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20040430

Year of fee payment: 17

REG Reference to a national code

Ref country code: FR

Ref legal event code: CD

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20050413

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20051101

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20050413

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20051230

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

Effective date: 20051230